Leioa (Lejona is the Spanish-language name, and the earlier official name in Spanish language) is a municipality in Biscay, Basque Country, in northern Spain. Today it is part of the Bilbao conurbation, and it is the name of a metro station in the Bilbao metro. Its population stands at approximately 28,400.

It was a village with no more than a 3000 people until fifty years ago, when development came its way, as Bilbao expanded. Today with a rapidly increasing population it is becoming part of metropolitan Bilbao.

The municipality of Leioa still retains much of its agricultural past and out of the urban centre many traditional Basque houses can still be seen on little family farms. Though rapid development puts their long term future in question. The University of the Basque Country (EHU-UPV Euskal Herriko Unibertsitatea - Universidad del Pais Vasco) has most faculties within this municipality.